International Journal of Biological Macromolecules, 2021
Two levels of chemically modified starches (starch citrates and lactates) prepared at 20% and 40%... more Two levels of chemically modified starches (starch citrates and lactates) prepared at 20% and 40% w/v concentration was subjected to extrusion to produce pregelatinized starches (PG). Starch citrates and lactates modified at 20% and 40% level were referred as (SC20 and SC40) and (SL20 and SL40), respectively. These PG starches underwent significant structural changes during extrusion as depicted by scanning electron micrographs. Native starches showed lower swelling power and water binding capacity but formed harder gels compared to chemically modified pregels. The dynamic rheology of these polymers (extruded modified starches) suggested visco-elastic property i.e. (G' > G''). Citrates demonstrated higher G' than lactates in both frequency and temperature sweep tests. Stability of storage moduli over entire temperature range confirmed that addition of citrates and lactates led to strengthening of gel structure through cross linking and esterification. Non-newtonian behavior was shown by all samples as determined through steady shear flow test with flow behavior index <1. Starch citrate (SC20-PG) demonstrated higher shear stress values. While, SC40-PG depicted anti-thixotropic behavior as measured through in-shear structural recovery measurements. On the basis of results obtained, the dual modification (chemical followed by extrusion) may impart fruitful applications in various food products.
Starch extracted from broken kernels of Basmati and Irri rice varieties of Pakistani rice were su... more Starch extracted from broken kernels of Basmati and Irri rice varieties of Pakistani rice were subjected to modification by addition of succinic anhydride at levels of 2%, 4% and 5% based on dried weight of starch. The succinyl content of Irri rice starch increased with the concentration of succinic anhydride. Scanning electron micrographs revealed presence of dents and fusion of rice starch granules. Swelling power and water retention capacity (WRC) significantly improved after succinylation while on refrigerated storage percent decline in paste clarity of modified rice starches was stable as compared to native Basmati (BC) and Irri (IC) rice starches. Succinylation also reduced solubility, pasting temperature (PT) and gel hardness of starch gels. Improvement was observed in cold storage stability of rice starch succinates as evident from textural profile analysis.
International Journal of Biological Macromolecules, 2021
Two levels of chemically modified starches (starch citrates and lactates) prepared at 20% and 40%... more Two levels of chemically modified starches (starch citrates and lactates) prepared at 20% and 40% w/v concentration was subjected to extrusion to produce pregelatinized starches (PG). Starch citrates and lactates modified at 20% and 40% level were referred as (SC20 and SC40) and (SL20 and SL40), respectively. These PG starches underwent significant structural changes during extrusion as depicted by scanning electron micrographs. Native starches showed lower swelling power and water binding capacity but formed harder gels compared to chemically modified pregels. The dynamic rheology of these polymers (extruded modified starches) suggested visco-elastic property i.e. (G' > G''). Citrates demonstrated higher G' than lactates in both frequency and temperature sweep tests. Stability of storage moduli over entire temperature range confirmed that addition of citrates and lactates led to strengthening of gel structure through cross linking and esterification. Non-newtonian behavior was shown by all samples as determined through steady shear flow test with flow behavior index <1. Starch citrate (SC20-PG) demonstrated higher shear stress values. While, SC40-PG depicted anti-thixotropic behavior as measured through in-shear structural recovery measurements. On the basis of results obtained, the dual modification (chemical followed by extrusion) may impart fruitful applications in various food products.
Starch extracted from broken kernels of Basmati and Irri rice varieties of Pakistani rice were su... more Starch extracted from broken kernels of Basmati and Irri rice varieties of Pakistani rice were subjected to modification by addition of succinic anhydride at levels of 2%, 4% and 5% based on dried weight of starch. The succinyl content of Irri rice starch increased with the concentration of succinic anhydride. Scanning electron micrographs revealed presence of dents and fusion of rice starch granules. Swelling power and water retention capacity (WRC) significantly improved after succinylation while on refrigerated storage percent decline in paste clarity of modified rice starches was stable as compared to native Basmati (BC) and Irri (IC) rice starches. Succinylation also reduced solubility, pasting temperature (PT) and gel hardness of starch gels. Improvement was observed in cold storage stability of rice starch succinates as evident from textural profile analysis.
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